Uncertainties in summer evapotranspiration changes over Europe and implications for regional climate change

Changes in summer evapotranspiration over central and eastern Europe are very uncertain in the World Climate Research Programme's (WRCP) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model data set. We show that the response of evapotranspiration in the future climate over this area is strongly linked to the way the models represent the respective role of soil moisture and radiative energy at surface on evapotranspiration at the interannual time scale in the present climate. Actually, the models for which the limiting effect of soil moisture upon evapotranspiration is already large in the present climate generally responds by a decrease of evapotranspiration whereas the other models generally exhibit an increase of evapotranspiration. The uncertainties in evapotranspiration changes seem to have an important impact in precipitation and temperature changes. Finally, we assess the realism of the controls of evapotranspiration in the CMIP3 models over France using a hydro-meteorological simulation.